S-Class (W140) 1991-1999: 300 SD, S 350TD, 300 SE 2.8, S280, 300 SE 3.2, 300 SEL 3.2, S320, S320L, 400 SE, S420, 400 SEL, S420L, 500 SE, S500, 500 SEL, S500L, 600 SE, S600, 600 SEL, S600L, 500 SEC, 600 SEC

heat loss on a 420 sel

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Old Feb 2, 2003 | 09:31 AM
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From: chester NY
1987 420 sel
heat loss on a 420 sel

HELP

Problem: No heat

Car mercedes 1987 420 SEL

How the problem appears

Start the car with the heat on i.e. the climate control wheel is on red and or MAX. Center console control on EC, or normal, or up and down hot air, heat is fine - WOW I mean hot. Thermostat is fine and new 80C MB original unit. With the car parked the heat will stay on forever. With the car parked rev up to over 20000RPM the heat dies and never comes back on. Restart the car the heat is instantly back. Backup to over 2000 RPM heat dies and stays dead. All this is with the heat control valve on MAX or 26C. Tuen the heat control valve back to white or green the heat turns off as it should. However, turn it back to red the heat does not restart EVER. Turn the engine off and on again heat is back and stays back. Rad flushed out. Whn you drive it the same symtpoms. Drive for 2 hours in the cold heat never comes on. PArk switch engine on and off revs below 2000 heat back on. What the hell is going on?
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